bio 2 ch28 t2

The unifying characteristics of protists

have nucleus, most are unicellular, wide range of nutritional strategies, mostly asexual

Discuss the evolutionary relationships between groups of protists and between protists and other eukaryotes

4 supergroups eukaryotes: Excavata, Sar Clade, Archeplastida, Unikonta

protists are a paraphyletic group meaning that

they include some but not all descendants of a common ancestor

The importance of endosymbiosis to evolution of photosynthetic eukaryotic groups

basically a host eukaryotic cell kept absorbing things and evolved into mitochondria then photosynthetic eukaryotes

gametic life cycle

typical in humans and animals, gametes are the only haploid cells, meiosis only occurs to produce the haploid gametes

sporic life cycle (alteration of generations)

this cycle allows for genetic variation and adaptation through sexual reproduction, the sporophyte undergoes meiosis to produce haploid spores, those spores germinate and grow into the gametophyte, the gametophyte produces haploid games through mitosis, fusion of gametes results in a diploid zygote, the zygote develops into a new sporophyte

zygotic life cycle

prevalent in most fungi and some protists, the only diploid stage is the single-celled zygote, haploid gametes fuse to form a diploid zygote, the zygote undergoes meiosis immediately, producing haploid cells, these haploid cels divide by mitosis leading to either unicellular descendants or a haploid multicellular organism, the haploid organism continues mitosis to produce cells that develop into gametes

explain how protists can be classified by ecological role

protists play key roles in ecological communities as symbionts and producers, ex. photosynthetic protists like diatoms are crucial producers in aquatic environments and symbiotic protists are vital for their hosts survival

explain how protists can be classified by habitat

most protists are aquatic, they can be planktonic or bottom dwellers or even inhabit most terrestrial environments like damp soil and leaf litter

explain how protists can be classified by motility

mechanisms such as flagella, cilia, and pseudopodia contribute to this

Identify members of the eukaryotic group excavata

includes several distinct protist groups characterized by unique features, ex. Diplomonads, Parabasalids, Euglenozoans

Diplomonads

protists with modified mitochondria, ex. Giardia intestinalis

Parabasalids

reduced motichondria, associated with symbioyic or parasitic lifestyles

Euglenozoans

this group is distinguished by their unique flagella structure, include a variety of species, some of which are photosynthetic while others are predatory

Identify members of the eukaryotic group Stramenopila

a major subgroup of the SAR clade, known for their significant role as photosynthetic organisms they are characterized by a unique flagellum with fine, hair-like projections, often paired with a shorter smooth flagellum, like Diatoms, Oomycetes, Brown Algae

Diatoms

unicellular algae with a distinctive glass-like wall made of silicon dioxide. They are abundant in oceans and lakes and are crucial photosynthetic organisms.

Oomycetes

Often referred to as water molds, these organisms resemble fungi and are known for their role in decomposition and plant diseases

Brown Algae

this group includes many seaweeds, such as kelp, which are important in marine ecosystems

Identify members of the eukaryotic group Alveolata

a subgroup within the SAR clade of eukaryotes, characterized by the presence of membrane-enclosed sacs (alveoli) located just under the plasma membrane, ex. Dinoflagellates, Apicomplexans, Cillates

Dinoflagellates

flagellated protists, often found in marine and freshwater environments. They are known for their cellulose plates and two flagella, which cause them to spin as they move

Apicomplexans

This group consists of parasitic protists, including Plasmodium, which causes malaria. They have complex life cycles often involving multiple hosts

Ciliates

These protists move using cilia, which are hair-like structures covering their surface are found in various aquatic environments and are known for their complex cellular structures

Identify members of the eukaryotic group Rizaria

subgroup within the SAR supergroup of protists, characterized by their unique threadlike pseudopodia, ex. radiolarians, forminferans, cercozoans

Radiolarians

these protists have intricate, symmetrical internal skeletons made of silica. Their pseudopodia radiate from the central body and are reinforced by microtubules, aiding in capturing prey

Foraminiferans

Known for their porous shells, or tests, made of organic material hardened with calcium carbonate. They use pseudopodia for movement and feeding, and often have symbiotic algae living within their tests

Cercozoans

This diverse group includes amoeboid and flagellated protists that feed using threadlike pseudopodia

Identify members of the eukaryotic group Ameoboza

they are a diverse group within the eukaryotic supergroup Unikonta. They are characterized by their lobe-shaped or tube-shaped pseudopodia, which they use for movement and feeding, ex. tubulinds, slime molds, entamoebas

Tubulinids

These are free-living amoebas found in various environments. They are known for their ability to move and capture prey using their pseudopodia

Slime Molds

they resemble fungi in producing fruiting bodies for spore dispersal, slime molds are more closely related to tubulinids and entamoebas. They are motile and ingest food, similar to animals.

Entamoebas

These are parasitic amoebas, including species that can infect humans and other animals

Identify members of the eukaryotic group Opisthokonta

diverse group within the eukaryotic supergroup Unikonta, ex. Animals, Fungi, Protists

Animals

Multicellular organisms that are a major part of the opisthokonts

Fungi

significant group within opisthokonts, known for their role in decomposition and symbiotic relationships

Protists

Several protist groups are part of the opisthokonts, including, Nucleariids, Protists closely related to fungi, Choanoflagellates, closely related to animals.

basic traits of chlorophytes

share structural and pigment similarities with plants, suggesting a close evolutionary relationship, primarily found in freshwater environments, range from unicellular organisms multicellular forms

ecological roles of chlorophytes

play significant roles in aquatic ecosystems, they contribute to phytoplankton communities, providing oxygen and serving as a food source for various aquatic organisms, some also live symbiotically with other eukaryotes, enhancing their hosts' food supply through photosynthesis.

evolutionary relationships of chlorophytes

they are part of the Archaeplastida group, sharing a common ancestor with charophytes and plants. This relationship is depicted in a phylogenetic tree, highlighting their evolutionary lineage within the green algae subgroup

basic traits of rhodophytes (red algae)

are primarily characterized by their reddish color due to phycoerythrin, which masks chlorophyll, they are mostly multicellular and thrive in marine environments

ecological roles of rhodophytes (red algae)

play crucial roles in marine ecosystems, they contribute to reef building through calcium carbonate deposition and serve as food and habitat for marine life

evolutionary relationships of rhodophytes (red algae)

they belong to the Archaeplastida group, sharing a common ancestor with green algae and plants

basic traits of plants

cuticles, stomata, multicellular dependent embryos, and walled spores produced in sporangia, they also exhibit alternation of generations and have apical meristems, which are regions of cell division at the tips of roots and shoots

ecological roles of plants

primary producers that convert sunlight into chemical energy via photosynthesis, creating food and oxygen for other life

evolutionary relationships of plants

they diverged into major groups: nonvascular plants (bryophytes), seedless vascular plants, and seed plants (gymnosperms and angiosperms)

basic traits of brown algae

they have unique structures resembling plant organs, such as rootlike holdfasts and stemlike stipes, they lack true tissues and organs they also have adaptations like gas-filled floats to keep their photosynthetic blades near the water surface

ecological roles of brown algae

They are vital for marine life, providing habitat and food. For humans, species like Laminaria are consumed as food, and algin from their cell walls is used to thicken processed foods

basic traits of diatoms

unicellular algae known for their unique glass-like walls made of silicon dioxide, which provide protection against predators

ecological roles of diatoms

they are crucial photosynthetic protists that significantly impact global carbon dioxide (CO₂) levels, they are also key producers in aquatic ecosystems, forming the base of food webs, they contribute to about 30% of the world's photosynthesis, supporting a wide range of marine life.

basic traits of dinoflagellates

they are characterized by membrane-enclosed sacs under their plasma membrane, their cells are often reinforced by cellulose plates, with grooves housing two flagella characterized by membrane-enclosed sacs under their plasma membrane, these flagella enable a spinning motion

ecological roles of dinoflagellates

About half of dinoflagellate species are heterotrophic, while others are key phytoplankton species, contributing to photosynthesis in aquatic ecosystems

primary endosymbiosis

process involving a heterotrophic eukaryote engulfing a cyanobacterium, leading to the formation of plastids with three membranes, this event is foundational for the evolution of red and green algae

secondary endosymbiosis

a process where a eukaryotic cell engulfs another eukaryotic cell that has already undergone primary endosymbiosis, this event is crucial in the evolutionary history of eukaryotes, particularly in the development of diverse protists

tertiary endosymbiosis

a complex evolutionary process where a eukaryotic host cell engulfs another eukaryotic cell that has already undergone secondary endosymbiosis, this process further diversifies the genetic and functional capabilities of the host cell

plastid

Organelles found in the cells of plants and algae, originating from endosymbiotic cyanobacteria

mitochondria

Organelles responsible for energy production in eukaryotic cells, believed to have originated from endosymbiotic bacteria

pseudopodia

Extensions of the cell membrane used by amoebas for movement and feeding

unikonta

A eukaryotic supergroup that includes amoebozoans and opisthokonts, closely related to fungi and animals

SAR claude

A diverse group of protists defined by DNA similarities, including stramenopiles, alveolates, and rhizarians

protozoa

Single-celled eukaryotes, often motile and heterotrophic

algae

Photosynthetic protists, including red and green algae, closely related to plants

mixotroph

Organisms that can obtain energy and nutrients through both photosynthesis and heterotrophy.

amoeba

Protists characterized by their ability to change shape using pseudopodia

flagella

Long, whip-like structures used for movement by some protists

cilla

Short, hair-like structures used for movement and feeding

haploid

A cell with a single set of chromosomes

diploid

A cell with two sets of chromosomes

gametophyte

The haploid phase in the life cycle of plants and algae that produces gametes

sporophyte

The diploid phase that produces spores in the life cycle of plants and algae

zygote

The diploid cell resulting from the fusion of two gametes

meiosis

A type of cell division that reduces the chromosome number by half, producing four haploid cells

mitosis

A type of cell division that results in two identical daughter cells, maintaining the chromosome number